Autumn 2000 Western Europe floods

The Autumn of 2000 was the wettest recorded in the United Kingdom since records began in 1766.[3][4][5]

Autumn 2000 Western Europe floods
Shrewsbury Abbey on 1 November
Datemid-September 2000— mid-December 2000[1]
LocationUnited Kingdom, Italy, France, Switzerland, Spain, Netherlands, Ireland, Denmark, Norway, Slovenia
Deaths20
Property damageEstimated to exceed $2 billion[2]

Several regions of Atlantic Europe from France to Norway received double their average rainfall and there were severe floods and landslides in the southern Alps.[6] In October and November 2000 a successive series of extratropical cyclones caused severe flooding across the UK.[7][8]

The United Kingdom saw the most extensive nationwide[9] flooding event since the snow-melt of 1947.[4] Prior to 1947, three similar events occurred in the second half of the 19th century where prolonged rainfall led to widespread flooding throughout England in the month of November, namely 1894, 1875, and 1852.[3]

The combined effect of the storms across Western Europe caused flooding throughout the United Kingdom. Two storm events (Nicole and Oratia) 28 October to 3 November, and the storm Rebekka from 4 November, resulted in continuous flooding.[10][11] 10,000 homes were flooded in 700 locations.[4] Peak flows on the Rivers Thames, Trent, Severn, Wharfe and Dee were the highest for 60 years. The River Ouse in Yorkshire reached the highest level since the 17th century.[4]

In the United Kingdom a series of severe floods affected large parts of the country in the Autumn of 2000. The worst affected areas were Kent and Sussex during October and Shropshire, Worcestershire and Yorkshire in November. The Autumn of 2000 was the wettest on record in the England and Wales precipitation record with several major rainfall events causing flooding in different parts of the country during October and November. England and Wales had an average of 503 mm of rain from September–November exceeding the previous record by nearly 50 mm.[12]

Meteorological background

A succession of slow-moving low pressure systems crossed the UK during Autumn 2000 associated with the jet stream being in a more southerly position than average.[13] The flooding in Kent and Sussex resulted from a succession of thunderstorms passing along a near-stationary front.[14] Much of the rock in this area is impermeable and there had already been significant rainfall in the south-east allowing for increased surface flow and river levels. Several fronts passed over central and northern England in the following weeks causing flooding in Shropshire, Worcestershire and Yorkshire.

Prelude

The rainfall for this period in the three preceding years had been above the 1961-1990 average.[14] The previous spring was unsettled, with April and May particularly wet,[8] which increased the aquifer recharge season.[14] Heavy rain was also seen in June, leading to high river levels and some flooding in Yorkshire.[8]

September 2000 was generally unsettled, with wet periods between 14-19. This resulted in some flooding on 15 September around Portsmouth and Southsea as a pumping station at Eastney failed after 58 mm (2.3 in) of rain fell in 4.5 hours, being the heaviest rain since 1986 in the area. Total rainfall was also measured at 65mm in Havant making this a 1 in 108 year storm event.[15] Storms affected Flanders in Belgium 15 September, with tornados reported in the municipalities of Zwalm, Antwerp and Erpe-Mere. Flooding affected the regions of Ghent and Kortrijk.[16] 24 out of 27 UK Met Office regions except northern Scotland received higher than normal rainfall during the month, making this the wettest September since 1981.[5]

Ex-Hurricane Isaac, 2–4 October

Ex-Hurricane Isaac crossed the Atlantic with eye still visible on 2 October[17] and lashed the west of the British isles with near gale-force winds on 3 October, before merging with another extra-tropical low on 4 October north of Scotland.[18] Early October 2000 brought more than the monthly average rainfall in the first 10 days to the southeast of England.[19]

Ex-Tropical Storm Leslie, 9–14 October
Ex-TS Leslie (Imke/Heidrun[20])
TypeEuropean windstorm
Extratropical cyclone
Formed7 October 2000
Dissipated14 October 2000
Lowest pressure963 mb (28.4 inHg)[21]
Highest gust0 km/h (0 mph) in
Areas affectedWestern Europe

A complex of low pressures, named Heidrun & Imke[22] by FU Berlin formed from the remnants of Tropical Storm Leslie. This formed at 30˚N 76˚W on 5 October, swept westwards and merged with a front on 7 October, and then reintensified to become a storm south of Great Britain with winds of 40-50 knots reported in the Bay of Biscay.[23] An area of convective storms stalled over Sussex and Kent.

  • 9 October: two complex low pressure systems brought more fronts and 25-40mm of rain over Sussex
  • 10 October: a Low developed over Scotland, with gales and heavy showers over Sussex bringing 10-15mm of rain
  • 11 October: the Low over Scotland became stuck, with a new Low arriving over Central England, producing gales over the whole UK and 15-30mm of rain over Sussex.
  • 12 October: the Low drew moist air from the Bay of Biscay over Southern England where a line of heavy, localised thundery showers formed. They tracked northwest over Sussex, bringing 150mm of rain overnight to Uckfield. Only 5-10mm fell in some other areas.[24]

Affected areas

Kent

Homes in Yalding and Maidstone were flooded, however there had been fears that a high tide might lead to the River Medway bursting its banks. This threat passed preventing much more widespread damage.[25] Evacuations took place in some villages in the county.

Sussex

On 12 October many roads were flooded across both West and East Sussex including the A21 and A22. A lifeboat crew rescued 20 people trapped in a supermarket in Uckfield and others were rescued by helicopter.[26]

Shropshire

Shrewsbury, Ironbridge and Bridgnorth flooded as the Severn breached its banks and reached its highest levels in 53 years.[27]

Worcestershire

The Severn breached its banks in many parts of the county, including at Bewdley, Worcester and Upton-upon-Severn. In Worcester, the Severn peaked on 3 November at its highest level in 53 years. The river remained in flood for several days however and the main road bridge in the city was closed. Homes were flooded in Diglis as well as many businesses on the city's waterfront and the cricket ground. In Bewdley, the floods led to renewed calls for flood defences in the town.[28] These were completed in 2006 and have since reduced the impact of flooding on the town.

Yorkshire
The Ouse in flood, York

Flooding affected York during the summer and autumn of 2000 as the River Ouse reached its highest levels since records began. The floods cost the city council in excess of £1 million and 40 people had to be moved from their homes.[29] The floods were the worst in 375 years; more than 300 homes were flooded and the army were called in to help with flood relief efforts.[30]

Aftermath

Warm sea surface temperatures in the English Channel and Norway,[31] along with an abnormally warm North Atlantic, added moisture and energy to weather systems as they crossed the UK.[8] September was the wettest since 1981, October the wettest since 1903 and November the wettest since 1970. Overall the autumn of 2000 was the wettest since 1872, and more rain fell in September, October and November than in any other 3-month period since rainfall records began in 1727.[8]

Government report

Defra commissioned an independent review by the Institution of Civil Engineers under George Fleming.[32] The review was to consider methods of estimating and reducing flood risk and look at whether flood risk management could make more use of natural processes. The resulting report entitled Learning to Live with Rivers specifically criticised a reluctance to use computer models and inadequate representation of the dynamic effects of land use, catchment processes and climatic variability. More broadly, the report noted that sustainable flood risk management could only be achieved by working with the natural response of the river basin and by providing the necessary storage, flow reduction and discharge capacity. It concluded that floods can only be managed, not prevented, and the community must learn to live with rivers.

The report found that damage was reduced by flood defences and by timely warnings and evacuations where the defences could not hold back the water. As a result, 280,000 properties were protected from the floods, but over 10,000 properties were still flooded at an estimated cost of £1 billion.

References
  1. "The UK record-breaking wet Autumn 2000" (PDF). UK Universities Global Atmospheric Modelling Programme Newsletter. Retrieved 27 February 2012.
  2. "Rising Temperatures Bringing Bigger Floods". Science Magazine. Archived from the original on 14 August 2011. Retrieved 15 March 2012.
  3. "Preliminary Report of U.K. Flood Damage From Increased Rainfall in November 2000" (PDF). Risk Management Solutions. Retrieved 24 February 2012.
  4. "The wet autumn of 2000". UK Met Office. Retrieved 24 February 2012.
  5. "The Autumn 2000 Rains and Floods" (PDF). UK Parliament briefing paper. Retrieved 24 February 2012.
  6. Blackburn, M.; B. J. Hoskins (2001). "Atmospheric variability and extreme Autumn rainfall in the UK" (PDF). met reading. Retrieved 24 February 2012.
  7. "unknown" (PDF). NERC. Archived from the original (PDF) on 16 December 2007. Retrieved 27 February 2012. Cite uses generic title (help)
  8. Paul Hudson. "The 10th anniversary of the Autumn 2000 floods". BBC. Retrieved 15 March 2012.
  9. "The 2000/01 Floods — a Hydrological Appraisal: Introduction and Overview". NERC. Archived from the original on 19 February 2007. Retrieved 24 February 2012.
  10. "What is a flood? Defining flood loss occurrences for reinsurance purposes" (PDF). Munich Re Group. Retrieved 22 February 2012.
  11. "Lessons Learned: Autumn 2000 floods". Archived from the original (PDF) on 27 September 2007. Retrieved 18 May 2009.
  12. Marsh T, Dale M (2002). "The UK floods of 2000-2001: A hydrometeorological appraisal". Journal of the Chartered Institute of Water and Environment Management. 16 (3): 180–88. doi:10.1111/j.1747-6593.2002.tb00392.x.
  13. Blackburn M, Hoskins B (2001). "Atmospheric variability and extreme Autumn rainfall in the UK" (PDF). Cite journal requires |journal= (help)
  14. "The UK Autumn 2000 floods". WWF/climateprediction.net. Archived from the original on 11 December 2011. Retrieved 24 February 2012.
  15. "Preliminary Flood Risk Assessment" (PDF). Portsmouth City Council. Archived from the original (PDF) on 30 September 2011. Retrieved 27 February 2012.
  16. "Inondations" (in French). Royal Meteorological Institute Belgium. Retrieved 9 April 2012.
  17. Donguy, Patrick; Daniel Pochic (May 2001). "Les photos du mois:De la ligne de grains à la tempête - Octobre 2000" (PDF). La Météorologie (in French). 33. Retrieved 23 March 2012.
  18. "Hurricane Isaac Tropical Cyclone Report". National Hurricane Center. NOAA. Retrieved 25 February 2012.
  19. "U.K. Floods, October 13-14, 2000" (PDF). Risk Management Solutions. Retrieved 24 February 2012.
  20. "Rétrospective Des Catastrophes Naturelles Survenues en 2001" (PDF) (in French). Munich Re Group. Retrieved 4 March 2012.
  21. "British Isles weather diary". reading.ac.uk. Retrieved 10 March 2012.
  22. "Schauer werden von stürmischen Böen begleitet" (in German). rp-online. Retrieved 4 March 2012.
  23. Mariners Weather Log (PDF). 45 (1). April 2001 http://www.vos.noaa.gov/MWL/apr2001.pdf. Retrieved 9 March 2012. Missing or empty |title= (help)
  24. "Uckfield Case Study: What caused the heavy rain of 12 October 2000?". Geographical Association. Archived from the original on 14 March 2009. Retrieved 25 February 2012.
  25. "Relief as flood threat eases". BBC. 14 October 2000. Retrieved 6 April 2012.
  26. "Floods cause chaos". BBC. 12 October 2000. Retrieved 6 April 2012.
  27. "Time shift: 2000 Floods". BBC Shropshire. Retrieved 2 April 2012.
  28. "Floods Round-up". Worcester News. Retrieved 2 April 2012.
  29. "York counts cost of 2000 flood". BBC. 13 August 2004. Retrieved 2 April 2012.
  30. Dennis, I. A.; MacKlin, M. G.; Coulthard, T. J.; Brewer, P. A. (2003). "The impact of the October-November 2000 floods on contaminant metal dispersal in the River Swale catchment, North Yorkshire, UK". Hydrological Processes. 17 (8): 1641. Bibcode:2003HyPr...17.1641D. doi:10.1002/hyp.1206.
  31. Benestad, R. E.; Melsom, A. (2002). "Is there a link between the unusually wet autumns in southeastern Norway and sea-surface temperature anomalies?". Climate Research. 23: 67–79. Bibcode:2002ClRes..23...67B. doi:10.3354/cr023067.
  32. Fleming, George; et al. (November 2001). "Learning to live with rivers". Institution of Civil Engineers. Archived from the original (PDF) on 9 January 2013. Retrieved 18 May 2012.
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